PART B: PRACTICAL WORK 10 Marks Write Your Answers In The Space Provided. Refer To The Following Information To Answer Question 1. The Concentration Of Hydrochloric Acid Can Be Determined By Using The Heat Produced During Neutralization. In An

Mar 10, 2025 by ADMIN 248 views

**PART B: PRACTICAL WORK**

10 Marks

Write your answers in the space provided. Refer to the following information to answer Question 1.

The concentration of hydrochloric acid can be determined by using the heat produced during neutralization.

In an experiment, 25 cm³ of hydrochloric acid (HCl) was added to 50 cm³ of sodium hydroxide (NaOH) solution. The temperature of the mixture was recorded before and after the addition of HCl. The temperature increased by 5°C.

Question 1: Calculate the concentration of hydrochloric acid (HCl) in the given solution.

To calculate the concentration of HCl, we need to use the heat produced during neutralization. The heat produced is given by the equation:

Q = mcΔT

where Q is the heat produced, m is the mass of the solution, c is the specific heat capacity of the solution, and ΔT is the change in temperature.

In this experiment, the mass of the solution is not given, but we can assume it to be constant. The specific heat capacity of the solution is approximately 4.18 J/g°C.

The change in temperature (ΔT) is given as 5°C.

We can now use the equation to calculate the heat produced (Q):

Q = mcΔT Q = (m)(4.18 J/g°C)(5°C) Q = 20.9 J

The heat produced (Q) is equal to the heat of neutralization (ΔH) multiplied by the number of moles of HCl (n) added to the solution.

The heat of neutralization (ΔH) for the reaction between HCl and NaOH is approximately 57.3 kJ/mol.

We can now use the equation to calculate the number of moles of HCl (n) added to the solution:

Q = nΔH 20.9 J = (n)(57.3 kJ/mol) n = 3.65 x 10⁻⁵ mol

The number of moles of HCl (n) added to the solution is 3.65 x 10⁻⁵ mol.

The concentration of HCl (C) can be calculated using the equation:

C = n/V C = (3.65 x 10⁻⁵ mol)/(25 cm³) C = 0.0146 M

The concentration of hydrochloric acid (HCl) in the given solution is 0.0146 M.

Question 2: Explain the principle behind the experiment.

The principle behind the experiment is the heat of neutralization. When an acid (HCl) reacts with a base (NaOH), heat is produced. The amount of heat produced is proportional to the number of moles of acid added to the solution.

In this experiment, the heat produced during neutralization is used to calculate the concentration of HCl in the given solution. The heat produced is measured by recording the temperature of the mixture before and after the addition of HCl.

The heat of neutralization (ΔH) for the reaction between HCl and NaOH is approximately 57.3 kJ/mol. This value is used to calculate the number of moles of HCl (n) added to the solution.

The concentration of HCl (C) can be calculated using the equation:

C = n/V C = (n)(57.3 kJ/mol)/(V) C = (3.65 x 10⁻⁵ mol)/(25 cm³) C = 0.0146 M

The concentration of hydrochloric acid (HCl) in the given solution is 0.0146 M.

Question 3: What are the limitations of this experiment?

The limitations of this experiment are:

The mass of the solution is not given, which makes it difficult to calculate the heat produced (Q).
The specific heat capacity of the solution is assumed to be constant, which may not be accurate.
The heat of neutralization (ΔH) for the reaction between HCl and NaOH is assumed to be constant, which may not be accurate.
The experiment assumes that the reaction between HCl and NaOH is complete, which may not be the case.

These limitations make it difficult to accurately calculate the concentration of HCl in the given solution.

Question 4: How can the experiment be improved?

The experiment can be improved by:

Measuring the mass of the solution accurately.
Using a more accurate method to measure the temperature of the mixture.
Using a more accurate value for the specific heat capacity of the solution.
Using a more accurate value for the heat of neutralization (ΔH) for the reaction between HCl and NaOH.
Ensuring that the reaction between HCl and NaOH is complete.

By improving the experiment, we can get a more accurate value for the concentration of HCl in the given solution.

Question 5: What are the applications of this experiment?

The applications of this experiment are:

Determining the concentration of hydrochloric acid (HCl) in a solution.
Measuring the heat of neutralization (ΔH) for the reaction between HCl and NaOH.
Understanding the principle behind the heat of neutralization.
Developing a method to measure the concentration of HCl in a solution.

This experiment has many applications in chemistry and other fields.

Question 6: What are the safety precautions that should be taken during the experiment?

The safety precautions that should be taken during the experiment are:

Wearing protective gloves and goggles to prevent skin and eye irritation.
Wearing a lab coat to prevent skin and clothing contamination.
Using a fume hood to prevent inhalation of fumes.
Handling the chemicals with care to prevent spills and accidents.
Following the proper procedures for disposing of chemicals and waste.

By taking these safety precautions, we can prevent accidents and ensure a safe working environment.

Question 7: What are the sources of error in the experiment?

The sources of error in the experiment are:

Inaccurate measurement of the mass of the solution.
Inaccurate measurement of the temperature of the mixture.
Assuming a constant specific heat capacity of the solution.
Assuming a constant heat of neutralization (ΔH) for the reaction between HCl and NaOH.
Incomplete reaction between HCl and NaOH.

These sources of error can affect the accuracy of the results and should be taken into account when interpreting the data.

Question 8: How can the experiment be modified to improve its accuracy?

The experiment can be modified to improve its accuracy by:

Using a more accurate method to measure the mass of the solution.
Using a more accurate method to measure the temperature of the mixture.
Using a more accurate value for the specific heat capacity of the solution.
Using a more accurate value for the heat of neutralization (ΔH) for the reaction between HCl and NaOH.
Ensuring that the reaction between HCl and NaOH is complete.

By modifying the experiment, we can improve its accuracy and get a more reliable value for the concentration of HCl in the given solution.

Question 9: What are the advantages of using this experiment to determine the concentration of HCl?

The advantages of using this experiment to determine the concentration of HCl are:

It is a simple and easy-to-perform experiment.
It requires minimal equipment and materials.
It can be performed in a short amount of time.
It provides a reliable and accurate value for the concentration of HCl.
It can be used to measure the concentration of HCl in a variety of solutions.

These advantages make this experiment a useful tool for determining the concentration of HCl in a solution.

Question 10: What are the disadvantages of using this experiment to determine the concentration of HCl?

The disadvantages of using this experiment to determine the concentration of HCl are:

It requires accurate measurement of the mass of the solution.
It requires accurate measurement of the temperature of the mixture.
It assumes a constant specific heat capacity of the solution.
It assumes a constant heat of neutralization (ΔH) for the reaction between HCl and NaOH.
It requires careful handling of the chemicals to prevent spills and accidents.

These disadvantages make this experiment a bit more challenging to perform, but the advantages make it a useful tool for determining the concentration of HCl in a solution.
Q&A: PART B: PRACTICAL WORK

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10 Marks

Write your answers in the space provided. Refer to the following information to answer Question 1.

The concentration of hydrochloric acid can be determined by using the heat produced during neutralization.

Q1: What is the principle behind the experiment?

A1: The principle behind the experiment is the heat of neutralization. When an acid (HCl) reacts with a base (NaOH), heat is produced. The amount of heat produced is proportional to the number of moles of acid added to the solution.

Q2: How can the concentration of HCl be calculated using the heat produced during neutralization?

A2: The concentration of HCl can be calculated using the equation:

C = n/V

where C is the concentration of HCl, n is the number of moles of HCl, and V is the volume of the solution.

The number of moles of HCl (n) can be calculated using the equation:

n = Q/ΔH

where Q is the heat produced and ΔH is the heat of neutralization.

The heat of neutralization (ΔH) for the reaction between HCl and NaOH is approximately 57.3 kJ/mol.

Q3: What are the limitations of this experiment?

A3: The limitations of this experiment are:

The mass of the solution is not given, which makes it difficult to calculate the heat produced (Q).
The specific heat capacity of the solution is assumed to be constant, which may not be accurate.
The heat of neutralization (ΔH) for the reaction between HCl and NaOH is assumed to be constant, which may not be accurate.
The experiment assumes that the reaction between HCl and NaOH is complete, which may not be the case.

Q4: How can the experiment be improved?

A4: The experiment can be improved by:

Measuring the mass of the solution accurately.
Using a more accurate method to measure the temperature of the mixture.
Using a more accurate value for the specific heat capacity of the solution.
Using a more accurate value for the heat of neutralization (ΔH) for the reaction between HCl and NaOH.
Ensuring that the reaction between HCl and NaOH is complete.

Q5: What are the applications of this experiment?

A5: The applications of this experiment are:

Determining the concentration of hydrochloric acid (HCl) in a solution.
Measuring the heat of neutralization (ΔH) for the reaction between HCl and NaOH.
Understanding the principle behind the heat of neutralization.
Developing a method to measure the concentration of HCl in a solution.

Q6: What are the safety precautions that should be taken during the experiment?

A6: The safety precautions that should be taken during the experiment are:

Wearing protective gloves and goggles to prevent skin and eye irritation.
Wearing a lab coat to prevent skin and clothing contamination.
Using a fume hood to prevent inhalation of fumes.
Handling the chemicals with care to prevent spills and accidents.
Following the proper procedures for disposing of chemicals and waste.

Q7: What are the sources of error in the experiment?

A7: The sources of error in the experiment are:

Inaccurate measurement of the mass of the solution.
Inaccurate measurement of the temperature of the mixture.
Assuming a constant specific heat capacity of the solution.
Assuming a constant heat of neutralization (ΔH) for the reaction between HCl and NaOH.
Incomplete reaction between HCl and NaOH.

Q8: How can the experiment be modified to improve its accuracy?

A8: The experiment can be modified to improve its accuracy by:

Using a more accurate method to measure the mass of the solution.
Using a more accurate method to measure the temperature of the mixture.
Using a more accurate value for the specific heat capacity of the solution.
Using a more accurate value for the heat of neutralization (ΔH) for the reaction between HCl and NaOH.
Ensuring that the reaction between HCl and NaOH is complete.

Q9: What are the advantages of using this experiment to determine the concentration of HCl?

A9: The advantages of using this experiment to determine the concentration of HCl are:

It is a simple and easy-to-perform experiment.
It requires minimal equipment and materials.
It can be performed in a short amount of time.
It provides a reliable and accurate value for the concentration of HCl.
It can be used to measure the concentration of HCl in a variety of solutions.

Q10: What are the disadvantages of using this experiment to determine the concentration of HCl?

A10: The disadvantages of using this experiment to determine the concentration of HCl are:

It requires accurate measurement of the mass of the solution.
It requires accurate measurement of the temperature of the mixture.
It assumes a constant specific heat capacity of the solution.
It assumes a constant heat of neutralization (ΔH) for the reaction between HCl and NaOH.
It requires careful handling of the chemicals to prevent spills and accidents.

Q11: What is the significance of the heat of neutralization in this experiment?

A11: The heat of neutralization is the amount of heat produced when an acid (HCl) reacts with a base (NaOH). In this experiment, the heat of neutralization is used to calculate the concentration of HCl in the solution.

Q12: How can the heat of neutralization be calculated?

A12: The heat of neutralization can be calculated using the equation:

ΔH = Q/n

where ΔH is the heat of neutralization, Q is the heat produced, and n is the number of moles of HCl.

Q13: What are the factors that affect the heat of neutralization?

A13: The factors that affect the heat of neutralization are:

The concentration of the acid and base.
The temperature of the solution.
The specific heat capacity of the solution.
The heat of neutralization of the acid and base.

Q14: How can the heat of neutralization be used to determine the concentration of HCl?

A14: The heat of neutralization can be used to determine the concentration of HCl by calculating the number of moles of HCl added to the solution. The number of moles of HCl can be calculated using the equation:

n = Q/ΔH

where n is the number of moles of HCl, Q is the heat produced, and ΔH is the heat of neutralization.

Q15: What are the advantages of using the heat of neutralization to determine the concentration of HCl?

A15: The advantages of using the heat of neutralization to determine the concentration of HCl are:

It is a simple and easy-to-perform method.
It requires minimal equipment and materials.
It can be performed in a short amount of time.
It provides a reliable and accurate value for the concentration of HCl.
It can be used to measure the concentration of HCl in a variety of solutions.